Dowel bar bearing



Oct. 19, 1937. R. c. YEOMAN 2,096,702

DOWEL BAR BEARING Filed Feb. 7, 1936 l TOR.

RAY Y OMAN.

IS AT TORN EY;

Patented Oct. 19, 1937 nowar. ma BEARING Bay 0. Yeoman, ChicagaIlL, as'aignor H. Jacobson, Evanston, Ill.

Application i ebruary I, 1936, Serial No. 62,784

Claims.

My present invention relates to the construction of bridges, masonry and concrete structures, and particularly to the building of concrete pavements, and more particularly to an improved 5 load transmission unit using a short dowel sni1g' 1y fitted within reinforced metal bearing sleeves that are embedded in and-anchored to the two adjoining slab structures such as shown and described in the co-pending application of Clifford H. Westcott, Serial No. 22,308, filed May 20, 1935.

The primary object of my invention is to provide a method, for transmitting a concentrated wheel load across the space intervening between adjoining concrete road slabs, whereby a plurality of armored dowels spaced in series and at intervals along the slab edge will support the slab edge against transverse local bending when acted upon by a single wheel load when applied to one slab and over any one of the dowels in the series; and further, to-produce a structure which will automatically proportion the load between the remaining dowels for any increase or decrease in the space intervening between the faces of the adjacent slabs occasioned by the movement of the slabs.

My present invention has these and other objects, all of which are explained in detail and may be more readily understood when read in conjunction with the accompanying drawing (one sheet) which illustrates a preferred embodiment of my invention, it being manifest that changes and modifications may be resorted to. without departure from the spirit of the claims forming a part hereof.

In the drawing:

Fig. l is a perspective view of a commercial type of expansion joint carrying a dowel bar structure of the wing anchored or armored type; Fig. 2 is a vertical section through the dowel bar bearings as shown in Fig. l, the dowel bar being shown in elevation and illustrating one method of application of my invention; and,

Fig. 3 is an enlarged fragmentary view similar to a portion of Fig. 2 exaggerating the position taken by the unit when the dowel is under full load.-

The structures illustrated involve the specific application of my invention to a roadway slab. For purposes of description only, I choose to so define my invention as applied to this particular construction; however, I wish it understood that my invention is equally eifective when adopted or used. in any poured or precast structure, whether it be a roadway slab, retaining wall, 66 swimming pool, reservoir, canal lining, warehouse floor, dock, industrial plant, sidewalk, driveway, airport run-way, bridge, etc., for, as a matter of fact, it is applicable to an almost unlimited number of structures.- And while I have described my invention in its preferred embodiment, it is to be further understood that the words which I have used are words of description and not of limitation.

For purposes of illustration only, I have shown a conventional type of expansion joint compris ing a stool consisting of spaced'side walls 55 closed atthe bottom and supporting a metallic seal 6 .with agmastic cap], the seal being pro- "vided with lateral anchors 8-9 adapted to be cast into adjoining concrete slab sections (not shown); and, whereas, I have shown and described such an expansion joint, I wish it understood that any type of expansion, contraction, or construction joint may be employed in conjunction with my invention.

. My invention consists in spanning the space intervening between the adjoining faces of the adjacent concrete slabs with a .series of relatively short dowel bars 10, positioned at substantially mid-depth of the slabs, parallel with the top surface thereof, normal to the plane of the joint, and spaced at regular. intervals throughout the width of the slab. The ends of the dowel are seated in a pair of sleeves or bearings l l-IZ which are reamed to provide a snug and tight sliding fit for the dowel and of a length sufiicient to provide an air chamber l3-l4 of a depth equivalent to at least one-half of thespace intervening between theadjoining slabs at the time of assembly. The outer ends of the sleeves are sealed with a wall l5i 6 and the inner faces 48 are cast approximately flush with the face of their respective slab section; a pair of radial arms .l.92ilr,protrude from the walls of the sleeves and .diverge therefrom, serving as anchors in their respective slabs.

My particular invention resides in the funneling, chamfering or countersinking of a portion of the dowel bar bearing starting at the face of the flanges l'l--l8 and extending back therefrominto the slabs as indicated at 2|. J

When an armored dowel, as above described, is used in concrete pavements which carry loads normal to the axis of the dowel, the unit acts or resists in pure shear only when joined slabs are closed or in contact. This condition is illustrated by the construction joint, contraction joint, or the closed expansion joint.

In the case of the open expansion joint where the slabs are separated by a definite space, a load on one slab at the joint ond over an armored dowel deforms the dowel in bending as well as in shear. Thebending of the dowel allows a greater displacement of one slab in respect to the other, giving flexibility to the load transmission unit at the joint.

Armored dowels are spaced along the transverse joint at sumcient intervals to support the slab edge against local bending when acted upon by single wheel loads. In the case of an expansion joint, a wheel load placed directly over an armored dowel on one side of the joint first bends the dowel and deflects the slab between the two adjacent dowel bearings. The flexibility of the dowel permits most of the load to be carried by the edge of the slab to the several pairs of armored dowels on each side of the loaded dowel. Thus the beam action of the edge of the slab carries approximately three-fourths of the load to the adjacent dowels when five dowels are placed inseries. In other words, the loaded dowel carries but one-fifth more than the average of the five dowels. As stated, this division of the load to the armored dowel units is principally due to the flexibility of the dowel bar across expansion space.

In the case of a construction joint, a contraction joint, or a closed expansion Joint, a load placed over an armored dowel on one side of the joint will transmitits load to the dowel and across the joint in pure shear only, since heretofore the square edged bearing of the sleeves formed a con-- tinuous tube from slab to slab out only by a plane between the two slabs. Theoretically, there would be no bending, but practically, there would be a very small amount after the sleeves and dowels had been deformed by the bearing pressures. Thisbendingistoosmalltopermit a tangible amount of the load to be sanded away from the loaded dowel by the edge of the slab as in the open expansion joint. Therefore, the loaded dowel would cany practically all of the proportional load going to the other slab. I

In order that the adjacent dowels in the contraction joint may be permitted to carry a portion of the load, I provide a free span or length of dowel between the sleeves or within the sleeves of the unit This may be accomplished in two ways, first, by setting the sleeves back within the joined structures leaving a net space for bending; and second, by tunneling, chamfering or countersinking (see Fig. 2) the sleeve opening in such a manner as to provide a free, unsupported dowel length at the mid-section between the slabs of a shown on the accompanying drawing describe my invention as applied in general to poured concrete-cast in situ; and, whereas, I have not shown the specific structure, I wish it understood that my invention is equally applicable to precast concrete, art marble, imitation stone, glass, terra cotta and many other similar products, or combinations thereof.

Having thus described my invention, what I claim as new and dedre to'secure by Letters Patent is:

1. A joint connecting adjoining concrete sections, a plurality of dowels bridging the joint and e the concrete sections, and. a bearing sleeve positioned on the end of and providing bearing for each dowel, a portion of the bearing of each sleeve being deformed to conform to the curvature of the dowel when the dowel is deformed under load.

2. A load transfer member for concrete roads and the like comprising the combination of a dowel and a sleeve telescopically engaging one end thereof, the sleeve providing a snug bearing for one portion of the dowel, and a curved bearing for a second portion of the dowel, the curvature of the bearing conforming .to the curve of the dowel. when the dowel is deformed under load.

3. An armored dowel consisting of a bar, a sleeve of rigid material having a chamber therein enclosing one end of the bar,'the chamber extending beyond the enclosed end of the bar, and the opposite end of the chamber being deformed to a curve conforming to the curvature of the bar when the bar is deformed under load.

4. A dowel element consisting of a rigid sleeve closed at one end and open at the opposite end, a. curved bearing surface provided thereon adjacent the open end thereof, the curvature of said bearing surface conforming to the curve of a dowel bar when under load.

5. In a device of the kind described the com- I bination of means for receiving a dowel bar, and an element formed thereon to a curve conforming to the curvature of the bar when the bar is deformed under load.

RAY C. YEOMAN. 

